Mortality and follow-up data for neonates weighing 500 to 800 g at birth.

Survival and development of immature premature neonates (birth weight, less than or equal to 800 g) at a single regional center were compared for 2 1/2 years, when such neonates' conditions were considered hopeless, and for the next 4 1/2 years, when aggressive therapy was used. During the first 2 1/2 years, two (4%) of 56 survived, one of whom was profoundly impaired. During the next 4 1/2 years, 65 (44%) of 147 survived. Of 65 survivors, 54 were followed up for at least one year: 43% were normal, 22% had mild developmental delays, and 19 (35%) were impaired. Of the 19 impaired, one was profoundly impaired and four were severely affected. The number of normal survivors and the high level of functioning of most of the impaired survivors suggests intensive care is as appropriate for neonates weighing 800 g or less as for more mature, severely ill newborns